A study was conducted to determine the presence of surface antigens on cultured cells of bovine ocular squamous cell carcinoma (BOSCC) by serological testing. Serum from cattle with plaque and malignant stages of disease were tested for reactivity with surface antigens of cultured autologous and allogeneic cells. Indirect immune fluorescence assays were conducted to determine the presence of antibodies towards these tumor cells. It was found that sera tested possessed antibodies to the cultured tumor cells. Further, no surface reactivity was observed when these sera were tested for reactivity with normal epithelial cells. Reactive sera were analyzed by absorption tests with autologous and allogeneic cells. Absorbed sera showed no reactivity to surface antigens or allogeneic cells. This study suggests that there might be a shared antigen among the cells from plaque and malignant lesions.